Various example embodiments relate to a semiconductor device, and more particularly, to a ZQ calibration method for retaining a calibration operation time in a memory device with a shared ZQ pin.
A swing width of signals is decreasing so as to minimize a transmission time of signals interfacing between semiconductor devices. As the swing width of the signals decreases, an effect of external noise on the semiconductor devices increases, and signal reflection that may be caused by impedance mismatching in an interface may be a serious problem. To solve the impedance mismatching, memory devices include ZQ pins to receive ZQ calibration commands from outside of the memory devices and perform ZQ calibration operations, thereby controlling impedance matching.
According to a trend of high capacity memory, a multichannel memory device may be provided in one package. The multichannel memory device includes a plurality of memory chips (or dies) independently operating through different channels. In the multichannel memory device, signal lines transmitting commands, addresses, and data for each memory chip configure a channel of each memory chip. Since the number of signal lines per channel causes overhead of a chip size, ZQ pins of memory chips may be shared in order to reduce the number of signal lines. In this case, a scheme for sufficiently retaining ZQ calibration operation time of each memory chips is useful during a period of time provided in a specification of the multichannel memory device.